Exhaust-fan



(No Model.)

W. M. DWIGHT.

EXHAUST PAN.

No. 318,884. Patented May 2,6, 1885.

Unirse dTaTes PATTTNT @Trice-g VILLIAM M. DWTIGHT, OF DETROIT, MICHIGAN.

EXHAUST-FAN.

'ECATON forming part of Letters Patent No. 318,884, dated May 2G, 1885.

Application flied January El, 1835. (No model.)

To (LZ 'whom it may concern:

lie it known that I, VILLIAM M. DWIGHT, a resident of Detroit in the county of Vayne and State of Michigan, having invented new and useful Improvements in Exhaust-Fans; and I hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, which form a part of this specification.

This invention relates to an improvement in exhaust-fans for carrying off debris-as, for instance, the shavings 'and sawdust from wood-working machines.

In many machines of this kind the dbris is often of a mixed characterthat is, larger pieces, such as knots, are often mixed with the finer shavings and sawdustand if one fan, asis frequently the case, has to do duty for several machines which produce a variety of d` bris, the present construction of exhaust-fans is generally found deficient in carrying capacity, for the following reason: As the path the debris has to follow into and through the fan forms a very abrupt turn at the inlet-opening, it is here that the larger and heavier debrissuch as pieces of board and knots-strike with their full force against the moving parts ofthe fan and lose all or a large part of their momentum, which represents a deadloss, as they have to gain that momentum anew; all other debris loses, also, part of its momentum, but the amount of such loss depends largely upon the nature of the fragments, and the result is, that a certain sifting process begins to take place,by which the lighter fragments are rapidly carried through the fan, while the heavier ones take a longer time, an d accumulate, there` by reducing the capacity of the fan by absorbing its power. Many fans from their construction also present opportunities for the more stringy fragments to hang up until they are accidentally dislodged again. Thus while the fan may give very satisfactory results with dbris of a uniform nature, it is frequently found deficient for exhausting debris of amine-d character; and it is the object of my invention to construct a fan especially adapted for this work; and the invention consist-s in the peculiar combinations and the construction and arrangement of parts hereinafter more fully described and claimedi In the drawings which accompany this specification, Figure l is a vertical central section through my'improved fan, and 2 is a detached perspective of the fan-wheel. Fig. 3 is a side elevation.

A is the fan-case, B is the suction-inlet, B is the outlet, C is the fan-wheel shaft, and D is the drive-pulley, all these parts being of known construction and operation. E is the fan-wheel, which is provided with the ordinary fan-blades, F, but the latter, instead of being secured to the end of spokes or spiderarms, as in the usual description of fans of that class, are secured near the rim of a disk, G. This disk has a hub, a, for securing it to the fan-shaft, and upon that side which faces the inlet it has secured to it the deilector H. This deliector is of a cone or rather conoidal shape, its base is concentrically secured to the disk, and its apex is in the center of motion. Its sides near the base gradually merge into the face of the disk, solas to present an unbroken and continuous face therewith. Instead of making the disk and the deiector in two parts,it would, however, serve the purpose aswell to omit the disk altogether and provide the deflector with a suitable hub for securing it to the fan-shaft.

I are spiral wings, which develop upon the face ofthe deiicctor from the center, or from points near and concentric to the center. There are preferably as many of these wings as there are fan-blades, and, increasing in width gradually from the center toward the fau-blades, they become of suiiicient width at their outer ends to furnish a support for the inner edges of the fan-blades, which are in any suitable way secured thereto. These spiral wings, following their development from the cent-er toward their outer ends, turn backward-that is, incline opposite to the line of direction of the fan-wheel.

It will be noticed that the arrangement of the parts is such that in operation the vortex of air created within the faircase between the fan-disk and the inlet is perfectly unobstructed, and the air, together with the lighter debris, can pass from the inlet` into the fair blades without meeting any obstacle to retard their motion. The deector is so far removed from the inlet that it is altogether outside of the vortex, and its presence or absence should have no inliuence upon the flow of air and lighter dbris, and therefore it must not be confounded with such deiectors designed to influence or regulate the air-vortex.

The heavier fragments of the dbris, which are projected by their momentum outside of the air-vortex, impinge against the deflector, and are either directly thrown into the fanblades, or they are caught up by the spiral wings and thrown into the fairblades; The spiral Wings, owing to the peculiar direction in which they run, create air-currents, Which pass more or less radially outward from the center, and their sweeping act-ien assists the spiral Wings and the dcilector to rapidly pass all dbris coming Within their sphere into the fan-wings, and prevents, especially, the hanging up of the stringy fragments of the dbris. This result is greatly enhanced by the presence of the delector, which prevents the formation ef a dead-air space in the center of the fan, and by the receding curve formed by the spiral Wings, which, although forming a necessary support for the fanwings, recede rapidly toward the face of the deliector, leaving the air-vortex perfectly unobstructed.

\Vhat I claim as my invention isl. In an exhaust-fan having` inlet and outlet apertures and revolving fan-blades, a series 'of spiral wings, I, arranged in front of the air-inlet and secured to the revolving` fan, for the purpose of serving as propeller-blades te forni a vacuum in front of the inlet, as set forth.

2. In an exhaust-fan, the combination of the :fan-blades F and the deilector H with receding spiral Wings l, developing from the center or from points near and concentric to the center of the deflector, and, gradually becoming wider, form supports for the inner ends of the said fan-blades, described.

3. In an exhaust-fan, and in combination with the defleetor H, the spiral wings I, developing from the center toward the outer edge of the detlector, so as to recede from the direction in which the fan-wheel moves, and, increasing in Width from the center toward the fan-blades, form outwardly-curved arms,

to which the fan-blades are secured, substantially as described.

4. ln an exhaust-fan, the combination of the fan-case A, the disk G, having the hub a, the fan-blades F, secured to said disk, and the deflector H, provided with spiral Wings I, also secured to said disk, substantially as and for the purposes specified.

In an exhaust-fan, the combination, with the case A, having an inlet and outlet-, ofthe disk G, having hub a, and extending nearly to the outer edge of the ease, the detiector H, secured to said disk, the fan-blades F, also secured to said disk, and the receding spiral Wings l, developing from the center toward the outer edge of said defiector, and forming supports for the inner ends of the fanblades, substantially as described.

VILLIAM M. DVIGHT.

Vit-nesses:

H. S. SPRAGUE, E. J. SGULLY.

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